1. Field of the Invention
The subject invention relates generally to cathode ray tubes and, in particular, to arrangements for precisely centering the electron gun of the cathode ray tube within the neck of the tube.
2. Description of the Prior Art
Two current expedients commonly used to center a cylindrical electron gun within the neck of a cathode ray tube (CRT) are adjustment and fixturing. With the adjustment method, three equally spaced springs inside the CRT neck serve to center the electron gun therein in a shock mounted fashion. Centering is accomplished by rotating the CRT about its axis on a lathe and adjusting the position of the electron gun therein so as to reduce the observed excursion of the electron gun to a minimum. Concentricity achieved by this method between the CRT neck and the electron gun mounted therein has been found to be off by as much as 0.016 inches TIR (Total Indicator Reading, measuring maximum excursion of gun during 360-degree rotation of CRT). Fixturing involves pre-centering the electron gun in a fixture which emulates the CRT neck, and is not suitable for miniature CRT's because of the room required for the necessary components.
Accordingly, it is a principal object of the present invention to provide improved alignment of an electron gun in the neck of a CRT over methods which are now available for miniature CRT's. A related object of the invention is to simplify the manner in which an electron gun is centered in the neck of a CRT.